Background: Discussing treatment risks has become increasingly important in medical communication. Still, despite regulations, physicians must decide how much and what kind of information to present. Objective: To investigate patients’ preference for information about a small risk of a complication of colonoscopy, and whether medical and personal factors contribute to such preference. To propose a disclosure policy related to our results. Design: Vignettes study. Setting: Department of Gastroenterology, Academic Medical Centre, the Netherlands. Patients: 810 consecutive colonoscopy patients. Intervention: A home-sent (...) questionnaire containing three vignettes. Vignettes varied in the indication for colonoscopy, complication severity and level of risk. Patients were invited to indicate their wish to be informed and the importance of such information. In addition, sociodemograhic, illness-related and psychological characteristics were assessed. Main outcome measurements: Wish to be informed and importance of information. Results: Of 810 questionnaires, 68% were returned. Patients generally wished to be informed about low-risk complications, regardless of the indication for colonoscopy or the severity of the complication. The level of risk did matter, though (OR = 2.48, SE = 0.28, p = 0.001). The information was considered less important if done for population screening purposes or diagnosis of colon cancer, if the complication was less severe (bleeding) and if the risk was smaller (0.01% and 0.1%). Patients’ information preference was also related to age, mood and coping style. Limitations: Difficulty of vignettes. Conclusions: Patients generally wish to be informed about all possible risks. However, this might become uninformative. A stepwise approach is suggested. (shrink)